[5] U.S. Route 30, a four-lane freeway, passes through the northern part of the borough, with access from College Avenue at the northeast edge of town.

According to the United States Census Bureau, Mountville has a total area of 0.85 square miles (2.2 km2), of which 0.7 acres (2,719 m2), or 0.12%, are water.

The west side of the borough is drained by Strickler Run, a westward-flowing direct tributary of the Susquehanna.

On January 11, 1814, Isaac Rohrer laid out the town that became known as Mountville, dividing it into 130 building lots, sold by lottery.

Located 4 miles (6 km) east of Columbia in West Hempfield Township on the Lancaster and Susquehanna Turnpike, Mountville was originally named "Mount Pleasant" because it was situated on an elevation affording a pleasant view of the surrounding countryside in every direction.

In 1842, when the first post office was established in the town, the name was changed to "Mountville" because the postal service already had another Mount Pleasant registered in Pennsylvania.

After several annexations of land adjoining the borough through the years since, Mountville now consists of just under one square mile of residential, commercial, industrial and public property.